The present invention relates to an apparatus for performing vacuum processing on a substrate to be processed, such as a semiconductor wafer, on a mounting stand that electrostatically attracts the substrate.
Steps for forming an integrated circuit on a semiconductor wafer include film formation and etching steps. In such vacuum processing, a wafer is mounted on a mounting stand within a vacuum chamber, but it is necessary to press the wafer onto the mounting stand to ensure that the wafer is maintained uniformly at a predetermined temperature by a temperature adjustment means that is provided in the mounting stand. Since it is not possible to use a vacuum chuck within a vacuum, means such as an electrostatic chuck is used to attach and hold the wafer to the surface of the mounting stand by electrostatic force.
The overall configuration of a plasma apparatus that uses electron cyclotron resonance (ECR), including a mounting stand, is shown in FIG. 13 by way of an example of a vacuum processing apparatus. This vacuum processing apparatus is configured in such a manner that microwaves at, for example, 2.45 GHz are supplied into the interior of a plasma generation chamber 1A, and a magnetic field of, for example, 875 Gauss is applied thereto by an electromagnetic coil 12, so that the mutual interaction between the microwaves and the magnetic field causes a high-density plasma to be formed from a plasma gas such as Ar or O2, to activate a film-formation gas such as SiH4 that has been introduced into a film-formation chamber 1B, thereby forming a film on a wafer W.
A mounting stand 10 is configured of a dielectric plate 15 provided on the upper surface of a main mounting stand body 13 made of a material such as aluminum, with an O-ring 14 therebetween made of a plastic such as Viton or Kalrez (both products of E. I. du Pont de Nemours and Co. Inc.). An electrode 16 formed of a metal such as tungsten is provided in the interior of this dielectric plate 15 in the vicinity of the surface thereof, with the configuration being such that this surface portion acts as an electrostatic chuck. In addition, a coolant passageway 17 is provided in the main mounting stand body 13 and a heater 18 formed of an electrode of a metal such as tungsten is provided within the dielectric plate 15.
Since neither of the surfaces of the main mounting stand body 13 and the dielectric plate 15is a completely flat surface, slight gaps will be formed between them if they are simply superimposed. This mounting stand 10 is placed in a vacuum, however, so these gaps will act as thermal insulating regions. The reason why the O-ring 14 is interposed therebetween is to ensure that helium can be supplied to the region enclosed by the O-ring 14, thus guaranteeing uniform thermal transfer.
The thus configured mounting stand 10 is designed to attract and hold the wafer W to the surface of the mounting stand by electrostatic force, as previously described, but it also plays the role of heating the wafer W to a predetermined temperature. The surface of the main mounting stand body 13 is adjusted to 150xc2x0 C. to obtain a reference temperature by passing coolant through a coolant passageway 17, and the temperature of the wafer is controlled to be constant by combining this action with that of the heater 18.
In the thus configured mounting stand 10, the O-ring 14 is provided between the main mounting stand body 13 and the dielectric plate 15, but this O-ring 14 is made of plastic and so has a temperature resistance of no more than 200xc2x0 C., which means that it will deteriorate if the temperature increases any further, so that it will become impossible to maintain the sealing properties thereof. It is therefore not possible to increase the temperature of the surface of the dielectric plate 15 that is in contact with the O-ring 14 to above 200xc2x0 C..
Since semiconductor devices are now being designed to operate at even faster speeds, there is a trend to form interlayer dielectric films of SiOF or CFx, which have lower permittivities than SiO2. Such an SiOF or CFx film can be formed by the above described ECR plasma apparatus, but the processing is at a higher temperature than that for an SiO2 film and thus the surface of the dielectric plate 15 is required to be maintained at a temperature of 320 to 400xc2x0 C. during the processing.
Since the dielectric plate 15 in this case is a sintered member, it is difficult to construct it to a greater thickness, so this thickness is limited to at most about a dozen mm. If the surface of the dielectric plate 15 of such a thickness is heated up to approximately 320xc2x0 C., the temperature of the rear surface of the dielectric plate 15 will be approximately 300xc2x0 C., which means that the above described mounting stand 10 cannot be used for such high-temperature processing.
The present invention was devised in the light of the above situation and has as an object thereof the provision of a vacuum processing apparatus that can support the provision of an O-ring or the like in the mounting stand during high-temperature processing, and which can also enable vacuum processing with a high level of surface uniformity.
The present invention achieves the above described object by providing a vacuum processing apparatus comprising a vacuum chamber and a mounting stand provided within the vacuum chamber for a substrate to be processed, wherein the mounting stand comprises a cooling portion having a cooling means and a dielectric plate provided on top of the mounting stand for supporting the substrate, and the supporting dielectric plate comprises a heater and an electrode that configures an electrostatic chuck for electrostatically attracting the substrate; wherein the vacuum processing apparatus further comprises: an intermediate dielectric plate linked to a surface of the cooling portion with an annular synthetic resin sealing member therebetween and having an electrode configuring the electrostatic chuck embedded in a surface thereof; and a system for supplying a fluid for thermal transfer into a region surrounded by the sealing member between the cooling portion and the intermediate dielectric plate; the supporting dielectric plate being linked to the surface of the intermediate dielectric plate by the electrostatic force of the electrostatic chuck of the intermediate dielectric plate.
The above described object of the present invention is also achieved by the provision of a vacuum processing apparatus comprising a vacuum chamber and a mounting stand provided within the vacuum chamber for a substrate to be processed, wherein the mounting stand comprises a cooling portion having a cooling means and a dielectric plate provided on top of the mounting stand for supporting the substrate, and the supporting dielectric plate comprises a heater and an electrode that configures an electrostatic chuck for electrostatically attracting the substrate; wherein the vacuum processing apparatus further comprises: an intermediate dielectric plate provided in contact with a surface of the supporting dielectric plate on the opposite side from a substrate support surface of the supporting dielectric plate; a system for supplying a fluid for thermal transfer to a linkage surface between the intermediate dielectric plate and the supporting dielectric plate; and a controller for adjusting a pressure of the fluid for thermal transfer to control the degree of thermal transfer between the intermediate dielectric plate and the supporting dielectric plate.
The above described object of the present invention is further achieved by the provision of a vacuum processing apparatus comprising a vacuum chamber and a mounting stand provided within the vacuum chamber for a substrate to be processed, wherein the mounting stand comprises a cooling portion having a cooling means and a dielectric plate provided on top of the mounting stand for supporting the substrate, and the supporting dielectric plate comprises a heater and an electrode that configures an electrostatic chuck for electrostatically attracting the substrate; wherein the vacuum processing apparatus further comprises: an intermediate dielectric plate provided in contact with a surface of the supporting dielectric plate on the opposite side from a substrate support surface of the supporting dielectric plate; and an electrode configuring an electrostatic chuck that is embedded in the intermediate dielectric plate, for linking together the cooling portion and the intermediate dielectric plate by electrostatic force.